For a variety of reasons, higher-sulfur-content fuels are now being used, particularly in marine engines. This high sulfur content leads to the formation, in the presence of oxygen, of corrosive sulfur acids, particularly sulfuric acid. To prevent damage to the engine from these sulfur acids, they must be neutralized with a basic material. This basic material is ordinarily an additive in the oil used to lubricate the engine. As higher-sulfur-content fuels are used, a greater and greater reservoir of alkalinity must be included in the lubricating oil to neutralize the acid. However, using conventional additives, such as calcium phenates, an increase in the amount of additive leads to an increase in ash formation, which is detrimental to the engine.
It is an object of this invention to provide a lubricating oil additive which is effective in neutralizing sulfur acids. It is a further object to provide an additive which can neutralize large quantities of these acids with lower resultant ash formation than for conventional additives.